It is known in the art to utilize various devices for depositing a profiled frame onto the periphery of a pane, such as an automobile glazing. These devices comprise supporting and displacing elements for the pane onto which the profiled frame is to be deposited, with the relative movement between pane and extrusion head along the edge of the pane being produced to place the frame on the peripheral edge of the pane. The relative movement along the edge is produced by displacement of one of the extrusion head or the pane, for example, by a robot. In either case, the head is supplied with fluid polymer from a reservoir. When the head moves relative to the pane, the supply of polymer accompanies its movement or is connected to the head by a flexible pipe connected to a fixed distributor. Movement of the edge of the pane relative to a fixed extrusion head is described in European Patent Applications EP-0 585 129 and EP-0 493 068. Many documents describe the technique of extrusion of a polymer frame onto the periphery of a plate, such as European Patent Applications EP-A-121 481 and EP-A-524 092.
The thickness tolerances of the panes are not negligible and it is therefore necessary for the extrusion heads of the above type to accept the thickest panes of a given type (i.e., an upper limit of the tolerance on the thickness). However, for all the panes of a smaller thickness, the fluid polymer can escape during extrusion through the slot or slots left free between the wall faces of the extrusion head and the surfaces of the pane. A deposit is thus left on the pane after extrusion, which must be removed in a supplementary phase of the production process.
Since the tolerance of automobile panes is not precisely controlled by the pane manufacturer, it is difficult to precisely place a polymer frame on the edge of the pane. To avoid this problem, U.S. Pat. No. 5,183,612 discloses the deposition of the polymer frame onto a dummy windshield which has controlled dimensions. After the frame has cured, it is removed from the dummy windshield and then placed on the glass pane. Also, the polymer frame must be bonded to the glass pane when placed thereon. This process is cumbersome and results in duplicative operation as well as handling and storage problems for the cured polymer frame.
Another difficulty of prior art devices is that a secure seal to the pane is not always achieved. This can result in the escape of polymer from between the seal and the glass surface. Furthermore, movement between the die head and the pane becomes difficult if the seal between the die head and the pane is too strong. The present invention resolves these problems in a simple yet efficient manner.